Well, I did not like many of the episodes to tell you the truth. Even though the episodes were made for a younger audience, I feel that the writing was often simplistic even by those standards. That being said, I did enjoy two episodes in particular.
My favorite episode would probably be the Big Longneck Test. I enjoy this episode because we get to see Shorty's leadership style in contrast with Littlefoot's. Even though both have obviously passed unofficial leadership tests (Littlefoot and the events of the first film; Shorty and leading the group of much younger longnecks prior to meeting up with Bron) the episode shows that Shorty has established a more authoritative leadership style, whereas Littlefoot had a more participatory style. Shorty's authoritatian style is what one would expect from one who, by necessity, had few equals (few friends, in this context) and had to lead subordinates (the very young longnecks) to safety, whereas Littlefoot's more participatory style is what one would expect from one who has had experience taking the contrasting and sometimes clashing personalities of a diverse group of individuals (the gang of five).
The differences between the two styles of leadership highlight some of the development that Littlefoot has had since the first film. In the first film Littlefoot had no leadership experience, which was apparent in his inability to resolve disputes and difficulty in motivating his companions. However, after the experience in the first film and the sequels, Littlefoot's leadership abilities, although inconsistent, were noticeably more robust in my opinion. This episode presents several questions for me: "Like Littlefoot, will Shorty begin to establish a more participatory style after dealing with others in a more evenhanded fashion, and thereafter have the maturity to perhaps pass the test one day?" and "Is Shorty's authoritarian leadership style actually best suited to his particular species?" It is important to note that we know rather little about the leadership structures of the various herds. Perhaps Bron's leadership test would not be suitable to test leadership qualities in other longneck species?
Wow, that was a lot of exposition! I had better move on to the rest of my reply.
My second favorite episode would have to be the Star Day Celebration. Since Ruby is my favorite character, I enjoyed the fact that it focuses on her and establishes how she got into the valley.
My least favorite would have to be The Bright Circle Celebration. I find the apparent moral of the episode to be absolutely abhorrent. Its message seems to be that those who dare to dissent in their beliefs are in the wrong and that one should simply adopt the established views of the community. I find that the story does a disservice to those with dissenting views.